A standard rock-drilling and bolting machine such as described in U.S. Pat. Nos. 3,246,705, 4,497,378, and 4,473,325 can be used for short-hole drilling and subsequently fitting these holes with bolts or split sets. Such a machine has a jumbo or base on which is mounted a pivotal turret in turn carrying a drill and a bolt impactor. Once a hole has been made by the drill, the turret is pivoted to align the impactor with it so that a bolt can be rammed into the hole. Adjacent the turret is a carousel that has a pair of cradle plates that carry the bolts to be set, and a transfer device is provided for loading the impactor with bolts as same are needed. Such a device is used to stabilize a mine roof or even in some situations a side wall.
Another machine is known that is used for long-hole drilling. Such holes are used mainly for the installation of cable bolts that themselves are set in grout. Long holes are drilled by an altogether different drilling apparatus that is able to fit a succession of extension steels to the bit to drill a hole that is many times longer than the bit itself. The long holes are also usable for setting charges, taking cores, or just setting very long retaining rods. While the depth of a short hole is invariably less than the floor-to-roof height of the drift, a long hole is invariably a multiple of this dimension, so that the equipment for performing these different drilling functions is radically different. In a standard operation the short holes are less than 4 m in length while the long holes can be well in excess of 10 m.
This duplication of equipment represents a fairly large cost, in particular as each piece of equipment can cost a vast sum of money and since each such driller/bolt setter must often work the very same area as the long-hole borer. Just getting the one piece of equipment out of the way for the other one to get in and work represents a significant amount of wasted time.